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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2021 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "shared-bindings/neopixel_write/__init__.h"
#include "bindings/rp2pio/StateMachine.h"
#include "common-hal/rp2pio/StateMachine.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/digitalio/DigitalInOut.h"
#include "supervisor/port.h"
uint64_t next_start_raw_ticks = 0;
// NeoPixels are 800khz bit streams. We are choosing zeros as <312ns hi, 936 lo> and ones
// and ones as <700 ns hi, 556 ns lo>.
// cycle. The first two instructions always run while only one of the two final
// instructions run per bit. We start with the low period because it can be
// longer while waiting for more data.
const uint16_t neopixel_program[] = {
// bitloop:
// out x 1 side 0 [6]; Drive low. Side-set still takes place before instruction stalls.
0x6621,
// jmp !x do_zero side 1 [3]; Branch on the bit we shifted out previous delay. Drive high.
0x1323,
// do_one:
// jmp bitloop side 1 [4]; Continue driving high, for a one (long pulse)
0x1400,
// do_zero:
// nop side 0 [4]; Or drive low, for a zero (short pulse)
0xa442
};
void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout, uint8_t *pixels, uint32_t num_bytes) {
// Set everything up.
rp2pio_statemachine_obj_t state_machine;
// TODO: Cache the state machine after we create it once. We'll need a way to
// change the pins then though.
uint32_t pins_we_use = 1 << digitalinout->pin->number;
bool ok = rp2pio_statemachine_construct(&state_machine,
neopixel_program, sizeof(neopixel_program) / sizeof(neopixel_program[0]),
12800000, // 12.8MHz, to get appropriate sub-bit times in PIO program.
NULL, 0, // init program
NULL, 1, // out
NULL, 1, // in
0, 0, // in pulls
NULL, 1, // set
digitalinout->pin, 1, // sideset
0, pins_we_use, // initial pin state
NULL, // jump pin
pins_we_use, true, false,
true, 8, false, // TX, auto pull every 8 bits. shift left to output msb first
true, // Wait for txstall. If we don't, then we'll deinit too quickly.
false, 32, true, // RX setting we don't use
false, // claim pins
false, // Not user-interruptible.
false, // No sideset enable
0, -1); // wrap
if (!ok) {
// Do nothing. Maybe bitbang?
return;
}
// Wait to make sure we don't append onto the last transmission. This should only be a tick or
// two.
while (port_get_raw_ticks(NULL) < next_start_raw_ticks) {
}
common_hal_rp2pio_statemachine_write(&state_machine, pixels, num_bytes, 1 /* stride in bytes */, false);
// Use a private deinit of the state machine that doesn't reset the pin.
rp2pio_statemachine_deinit(&state_machine, true);
// Reset the pin and release it from the PIO
gpio_init(digitalinout->pin->number);
common_hal_digitalio_digitalinout_switch_to_output((digitalio_digitalinout_obj_t *)digitalinout, false, DRIVE_MODE_PUSH_PULL);
// Update the next start to +2 ticks. This ensures we give it at least 300us.
next_start_raw_ticks = port_get_raw_ticks(NULL) + 2;
}
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